Conventional "on-edge" mail stacking systems are usually composed of a transport followed by various forms of stacking mechanisms. Generally, multi-bin on-edge stacking systems include gating mechanisms which divert specific mailpieces into predetermined stacker bins. Such on-edge stacking systems are well known. The overwhelming majority of these systems stack mailpieces received in a vertical orientation on a horizontal surface.
Typically, in an on-edge stacking device envelopes are transported vertically along a dual belt transport system, deflected into a stacker bin by a deflector mechanism, and guided into the bin by conventional guide and urging components. The envelopes always stop against some sort of vertical registration surface. The integrity of the on-edge stacking is facilitated by a flat surface, commonly referred to as a paddle, that is orthogonal to the registration surface and is generally spring loaded to maintain a tight stacking of the envelopes against the guide component.
The conventional guides are generally flat surfaces that are made of low abrasive material so as not to interfere with the envelope being urged to the registration surface. Such conventional guides have proved to be suitable for guiding most envelope types. However, problems have been experienced when the on edge stacker is stacking envelopes having external side seams. Such problems are caused by the normal force applied to the stack by the paddle which maintains a tight stack against the guide between the urging component and the registration surface. The lead edge of an envelope being urged toward the registration surface has a tendency to get caught in the side seam of the previous envelope so urged, thus preventing the former envelope from ever reaching the registration surface. At a minimum, this results in an uneven stacking of the envelopes that requires special attention of an operator. Even worse than the uneven stacking is that a jam may occur in the stacking bin.
It is an object of the present invention to provide an improvement to the stacker that eliminates the aforementioned problems.